Nozzle for electrostatic powder spraying apparatus

ABSTRACT

A spray nozzle for use with an electrostatic powder spray gun for coating objects in an electrostatic field. The nozzle includes an electrically non-conductive nozzle body for releasable attachment to the front end of a spray gun. An electrically non-conductive carrier member is operatively mounted in the front end of the nozzle body. The carrier member is provided with a powder diffusing chamber of diverging outward conical shape. An electrical charging means is operatively mounted in said chamber. The outer end of the chamber is enclosed by a nozzle nose provided with a plurality of discharge ports. An adjustable powder spray flow control sleeve is slidably mounted around said nozzle nose in a concentric manner for axial adjustment to various positions to control the spray pattern of the powder as it is discharged from the nozzle nose.

United States Patent [1 1 Clausen et al.

[ 1 Oct. 23, 1973 NOZZLE FOR ELECTROSTATIC POWDER SPRAYING APPARATUS I inventors: Claus Clausen, Odense, Denmark; Frederick K. Jensen, Farmington,

Mich.

[73] Assignee: Elektro-lon, 1nc., Farmington, Mich.

[221 Filed: Mar. 23, 1972 [21] Appl. No.: 237,439

52 US. Cl. 239/15 [51] Int. Cl. B05b 5/02 [58] Field of Search 239/15; 317/3, 262R [56] References Cited UNITED STATES PATENTS 3,065,106 11/1962 Rhodes et al. 2391/15 UX 3,498,541 3/1970 Taylor et al. 239/15 3,540,653 11/1970 Fabre 239/15 3,085,749 4/1963 Schweitzer et al 239/15 3,117,029 1/1964 Hines' 239/15 FOREIGN PATENTS OR APPLICATIONS 1,578,913 8/1969 France 239/15 Primary Examiner-M. Henson Wood, Jr. Assistant Examiner-A. Kashnikow Attorney-Donnelly, Mentag & Harrington 57 ABSTRACT A spray nozzle for use with an electrostatic powder spray gun for coating objects in an electrostatic field. The nozzle includes an electrically non-conductive nozzle body for releasable attachment to the front end of a spray gun. An electrically non-conductive carrier member is operatively mounted in the front end of the nozzle body.'The carrier member is provided with a powder diffusing chamber of diverging outward conical shape. An electrical charging means is operatively mounted in said chamber. The outer end of the chamher is enclosed by a'nozzle nose provided with a plurality of dischargeports. An adjustable powder spray flow control sleeve is slidably mounted around said nozzle nose in a concentric manner for axial adjustment to various positions to control the spray pattern of the powder as it is discharged from the nozzle nose.

29 Claims, 19 Drawing Figures PATENIEU 061 2 3 ms SHEET 1 [1F 4 PATENTEBnma ms 3167.1 16

SHEET 3 BF d I) vs WWI/l.

PAIENIEUnma ms 3,767.1 1.6

SHEET l UF 4 NOZZLE FOR ELECTROSTATIC POWDER SPRAYING APPARATUS BACKGROUND OF THE INVENTION The art of electrostatic powder coating is well known, and it comprises coating objects in an electrostatic field with particles of ionized powder blown by an air stream from an electrostatic powder spraying apparatus provided with a spray nozzle. The powder is blown from the nozzle at a relatively high speed, and a disadvantage of the prior art spray nozzles is that they are not capable of providing a precise pattern control over the discharged ionized powder. A further disadvantage of the prior art electrostatic powderspray nozzles is that the entire nozzle comprises the charging media and because of the large mass of the nozzle, a charge is present on the nozzle'for a long interval after the gunis shut off. A further disadvantage fo the prior art powder spray nozzles is that some of them are so constructed and arranged that. it is a long and tedious process to disassemble them to clean the components thereof in order to change colors, and still others cannot be disassembled and must be chemically cleaned.

In view of the foregoing, it is an'important object of the present invention to provide an electrostatic powder spray nozzle which overcomes the aforementioned disadvantages of the prior art electrostatic spray nozzles. i

It is another object of the present invention to provide an electrostatic powder spray nozzle which is simple and compact in construction, and which'may be quickly and easily disassembled for an efficient and quick cleaning thereof when it is desired to change colors.

It is a further object of the present invention to provide an electrostatic powder spraynoZzIe which is'light in weight and has less mass than the prior art nozzles so that it does not hold a charge for any long interval after'the spray gun is turned off.

It is still another object of the present invention to provide an electrostatic powder spray nozzle which includes means for providing a precise pattern control over the powder flow when it is discharged from the nozzle.

It is still a further object of the present invention to provide an electrostatic powder spray nozzle which is provided with means for precisely controlling the powder flow and pattern thereof as it discharges from the nozzle under a constant air control pressure.

It is another object of the present invention to provide a powder spray nozzle that includes an electrically non-conductive nozzle body for releasable attachment to an electrostatic powder spray gun and which has operatively mounted in the front end thereof an electrically non-conductive carrier member provided with an axially disposed powder diffusing chamber formed therein which has a diverging outwardly conical shape. The powder diffusing chamber is open at its outer end and connected at its inner end to a pressurized source of coating powder. An electrical charging means is operatively mounted in a said powder diffusing chamber, and an electrically non-conductive diffusing nozzle nose is operatively mounted over the outer end of said chamber.

Other objects, features and advantages of this invention will be apparent from the following detailed description, appended claims, and the accompanying drawings.

SUMMARY OF THE INVENTION This invention relates generally to apparatus for applying powder coatings to articles in an electrostatic field, and more particularly, to an improved spray nozzle for an electrostatic powder spray gun.

The nozzle of the present invention is constructed and arranged for use with an electrostatic powder spray gun for coating objects in an electrostatic field. The spray gun is of a conventional type which includes an insulating barrel in which is carried a powder supply conduit connected to a pressurized source of coating powder, an atomizing air conduit connected to a source of pressurized atomizing air, and an electrical conductor means operatively connected to a source of electrical power.

The nozzle includes an electrically non-conductive nozzle body for releasable attachment at the front end of the spray gun. In one embodiment, an atomizing air chamber is formed in the front end of the nozzle body and an electrically non-conductive carrier member is operatively mounted in the front end of the nozzle body and has its inner end extended into the atomizing air chamber. The carrier member is provided with a powder diffusing chamber for diverging outward conical shape, and said chamber communicates with the atomizing air chamber through a plurality of ports which are located through, the inner end of the conically shaped walls of said diffusing chamber, whereby the atomizing air is applied to powder passing through the diffusing chamber at a point where the powder is expanding, and thus optimum charging of the powder and atomizing of the powder is provided. In another embodiment, the atomizing air chamber is deleted.

At least one electrical charging needle is longitudinally disposed in said diffusing chamber, and it is preferably axially disposed. The outer end of the diffusing chamber is enclosed by a nozzle nose provided with a plurality of discharge ports. An adjustable powder spray flow control sleeve is slidably mounted around said nozzle nose in a concentric manner for axial adjustment to various positions to control the spray pattern of the powder as it is discharged from the nozzle nose. The spray flow control sleeve and the nozzle nose are adjustable relative to each other by any suitable means, whereby these two parts may be adjusted relative to each other to provide various flow control patterns of the discharged powder.

In one nozzle nose embodiment the outer end surface of the nozzle nose is conically shaped with the discharge ports being disposed at an angle to the longitudinal axis of the nozzle nose and perpendicular to the surface of the conical end. This nozzle nose embodirnent provides an elongated powder spray flow pattern which is conically shaped and circular in cross section, and which comprises a plurality of projected thin lines. The positions of the nozzle nose and the spray flow control sleeve are adjustable relative to each other to increase the range of the spray pattern in order to spray more powder in hard-to-reach places on a workpiece, such as corners and depressions.

In another nozzle nose embodiment the nozzle nose includes a construction in which the discharge ports are arranged in an elongated diametrical line across a convex outer end surface, which line is perpendicular to the longitudinal axis of the spray nozzle, so as to provide a fan shaped powder spray pattern. Relative movement between the spray flow control sleeve and the nozzle nose also permits variation of the powder spray pattern, and the range of the spray pattern can be increased to spray additional powder in hard-to-reach places, such as corners and depressions. One or more electrical charging needles is operatively mounted in the carrier chamber for this nozzle nose embodiment.

The powder spray flow control means or sleeve may be adjusted manually by grasping the same and moving it or it may be adjusted by means operated from the spray gun.

In some embodiments, the electrical charging means in the carrier chamber has a portion that extends through the outer end surface of the nozzle nose.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a broken, sideelevational view of an electrostatic powder spray gun provided with a spray nozzle made in accordance with the principles of the present invention.

FIG. 2 is an enlarged side elevational view of the spray nozzle illustrated in FIG. 1, and showing the nozzle detached from the gun.

FIG. 3 is a fragmentary, side elevational view of the front end of the nozzle of FIG. 2, and showing the adjustable powder spray flow control sleeve moved to an adjusted forward position.

FIG. 4 is a right side elevational view of the structure illustrated in FIG. 2, taken along the line 4-4 thereof, and looking in the direction of the arrows.

FIG. 5 is an elevational section view of the structure illustrated in FIG. 4, taken along the line 55 thereof, and looking in the direction of the arrows.

FIG. 6 is a left side elevational view of the structure illustrated in FIG. 2, taken along the line 66 thereof, and looking in the direction of the arrows.

FIG. 7 is a top plan view of a second embodiment of the invention.

FIG. 8 is an elevational section view of the structure illustrated in FIG. 7, taken along the line 8-8 thereof, and looking in the direction of the arrows.

FIG. 9 is an elevational section view of the structure illustrated in FIG. 7, taken along the line 9-9 thereof, and looking in the direction of the arrows.

FIG. 10 is an elevational, section view of a modified nozzle nose of the type illustrated in FIGS. 1 through.

5, and showing such a nozzle nose provided with a plurality of annular rows of discharge ports.

FIG. 11 is a right side elevational view of the nozzle nose illustrated in FIG. 10, taken along the line 11-11 thereof, and looking in the direction of the arrows.

FIG. 12 is an elevational, section view of a spray nozzle made in accordance with the principles of the present invention, and showing a modified embodiment with the atomizing air chamber deleted.

FIG. 13 is a fragmentary, side elevational view, partly in section, of a spray nozzle made in accordance with the principles of the present invention, and showing the nozzle nose of FIGS. 7 through 9 being employed with three electrical charging needles.

FIG. 14 is a right side elevational view of the structure illustrated in FIG. 13, taken along the line l4--14 thereof, and looking in the direction of the arrows.

FIG. 15 is a fragmentary, side elevational view, partly in section, of a spray nozzle made in accordance with the principles of the present invention, and showing the nozzle nose of FIGS. 7 through 9 being employed with two electrical charging needles.

FIG. 16 is a fragmentary, elevational section view of a spray nozzle made in accordance with the principles of the present invention, and showing the nozzle nose of FIGS. 2 and 5 provided with a single electric charging needle that protrudes through the tip of the nozzle nose.

FIG. 17 is a fragmentary, elevational section view of a spray nozzle made in accordance with the principles of the present invention, and showing the nozzle nose of FIGS. 2 and 5 provided with a pair of electrical charging needles which are interconnected and provided with an extension that protrudes through the tip of the nozzle nose.

FIG. 18 is a fragmentary, elevational section view of a spray nozzle made in accordance with the principles of the present invention, and showing the nozzle nose of FIG. 15 provided with a pair of electrical charging needles which are interconnected and provided with an extension that protrudes through the outer surface of the nozzle nose.

FIG. 19 is a front end elevational view of the structure illustrated in FIG. 18, taken along the line 1919 thereof, and looking in the direction of the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, and in particular to FIG. 1, the numeral 10 generally designates a conventional electrostatic powder spray gun on which is operatively mounted a first embodiment spray nozzle made in accordance with the principles of the present invention, and generally indicated by the numeral 11. The gun 10 includes an elongated barrel 12, in the form of an insulating tube, on the front end of which is slidably mounted, by a slip friction fit, the rear end of the spray nozzle 11. The gun 10 includes a cylindrical clamp means 13 which is mounted around the rear end of the gun barrel 12, and which is operatively attached to the upper end ofa handle 14. The handle 14 carries a suitable trigger control switch means 15, and it is grounded by a suitable lead 16.

The gun 10 is operatively connected by a suitable electrical conductor or cable 17 to a suitable high voltage electrical power supply. The gun 10 is supplied with suitable coating powder under pressure by means of a powder supply conduit 18 which is adapted to be connected to a suitable source of pressurized coating powder. The gun I0 is further provided with an atomizing air conduit 19 which is adapted to be connected to a suitable source of pressurized atomizing air.

A suitable conventional electrostatic powder spray gun 10 is available on the market from Elektro-Ion, Inc. of 24115 Industrial Park Drive, Farmington, Michigan 48024, and it is illustrated in that companys bulletin E103. The powder spray nozzle of the present invention is adapted to be used for spraying any suitable powder used in conventional electrostatic powder spray guns.

As shown in FIG. 2, the spray nozzle 11 includes an electrically non-conductive nozzle body 20, which is circular in cross section, and which may be made from any suitable plastic material and the like. An axial inwardly extended mounting recess 21 is formed in the rear end of the nozzle body 20 and the inner end thereof is indicated by the numeral 22. The recess 21 is adapted to slidably receive the front end of the gun barrel 12 in a sliding friction fit to retain the spray nozzle 11 in place during a powder spraying operation.

As shown in FIGS. 2 and 5, the front end of the spray nozzle body is provided with an axial, inwardly extended atomizing air chamber 23 which extends inwardly to a point indicated by the numeral 24. The peripheral surface of the body 20 is reduced in diameter at its front end, and such surface is provided with external threads indicated by the numeral 25.

The mounting recess 21 and the atomizing air chamber 23 are interconnected by a threaded axial passage 26. An electrically non-conductive tube 27, made from any suitable material, as from a plastic material, is provided with an enlarged inner end 28 which is threadably mounted in the rear end of the axial passage 26. As shown in FIG. 2, the rear end of the tube 27 is slidably mounted in a tight friction fit in the inner end of the powder supply conduit 18.

The mounting recess 21 and the atomizing air chamber 23 are also interconnected by a second longitudinal passage 29 which is disposed radially outward from the tube 27. An electrically non-conductive tube 30, made from any suitable material, as a plastic material, is disposed with its inner end threadably mounted in the rear end of the passage 29. The atomizing air conduit 19 is operatively connected to the rear end of the tube 30 (FIG. 2) for supplying atomizing air under pressure to the chamber 23.

As shown in FIGS. 2 and 5, an electrically nonconductive carrier member, generally indicated by the numeral 311, is operatively mounted in a concentric axial position in the front end of the nozzle body 20. The carrier member 31 is made from any suitable material, as a plastic material. The carrier member 31 includes an outer cylindrical body portion 32 (FIG. 5) which has an outer end designated by the numeral 33. The carrier member body portion 32 is provided at its inner end with a radially outward projected flange 34. lntegrally formed on the inner end of the carrier body portion 32 is a first cylindrical extension 35 of a reduced diameter which extends rearwardly into the atomizing air chamber 23, with the flange 34 abuting the abutting end of the nozzle body 20. A conductor ring 36, made of any suitable conductive material, is fixedly mounted around the inner end of the carrier member extension 35. A further reduced diameter, threaded integral carrier member extension 37 is formed on the rear end of the first carrier member extension 35, and it is threadably mounted in the front end of the threaded passage 26. It will be seen that the carrier member 31 is thus threadably mounted in the nozzle body 20 by means of said inner reduced diameter carrier member extension 27.

As best seen in FIG. 5, the carrier member 31 is provided with an axially disposed powder diffusing chamber 38 which is formed in the carrier body portion 32 and the first reduced extension portion 35. The powder diffusing chamber 38 is open at the front end thereof and it is conically shaped and diverges outwardly. The inner end of the conically shaped powder diffusing chamber 38 is indicated by the numeral 39. A cylindrical axial passage 40 communicates the chamber 38 with the powder supply tube 27, from the chamber inner end 39 through the second reduced diameter carrier extension member 37.

A plurality of atomizing air ports 41 (FIG. 5) are formed through the wall of the first reduced diameter extension portion 35 to communicate the atomizing air chamber 23 with the powder diffusing chamber 38. The ports 41 are located in circumferentially, equal spaced apart positions forward of the inner end 39 of the conically shaped powder diffusing chamber 38. In one embodiment, six atomizing air ports 41 were used. It will be seen that the ports 41 are located in a position in the powder diffusing chamber 38 so that they will admit atomizing air to this chamber at a point where the powder under pressure has already entered chamber 38 and expanded to a certain extent. The admission of the atomizing air at this point in the powder diffusing conical chamber 38 provides optimum turbulence and dispersion of the powder.

As shown in FIGS. 2 and 5, an electrical charging means is provided which includes a charging needle or electrode 42 that has an outer end portion longitudinally disposed in the powder diffusing chamber 38 and in a central or axial position. The charging needle 42 is disposed with its outer pointed end in a position even with the outer end 33 of the carrier member 31. An intermediate portion of the needle 42 extends inwardly and outwardly and is integral with an inner end portion that is longitudinally disposed and which passes into the structure of the carrier body portion 32 and through the first carrier member extension 35 and into an electrical connection with the conductor ring 36. High voltage power is supplied to the conductor ring 36 through a suitable spring biased contact 46 which is operatively connected to the electrical cable 45 (FIG. 5) in the electrical conductor means 17.

As best seen in FIG. 5, a guide collar 47 is provided with a threaded inner end bore 49 for threadably mounting this collar on the threaded periphery 25 of the nozzle body 20. A smaller, smooth surface diameter bore 48 is formed through the outer end of the collar 47 and it forms a shoulder at its inner end with the larger threaded bore 49 which is adapted to be seated on the flange 34 when the collar 47 is threaded fully in place onthe body 20. The smooth surface bore 48 is larger in diameter than the outer diameter of the carrier body portion 32.

As shown in FIGS. 2 and 5, a'nozzle nose, generally indicated by the numeral 50, is slidably mounted over the outer end of the carrier body portion 32 and it extends into the bore 48 in the collar 47 and rests on the flange 34 of the carrier body portion 32. The nozzle nose 59 includes a cylindrical body 51 and a conical outer end surface or tip 52. The body 51 isprovided with an inwardly extended cylindrical chamber 53 which extends from the rear end of the nozzle nose inwardly into the body 51 and to the point 54 in the tip 52. Formed in the tip 52, at a point adjacent the inner end of the tapered outer surface of the conical tip 52 area plurality of peripherally disposed discharge ports 55 which are circumferentially and evenly spaced, and which angle outwardly approximately 45 relative to the longitudinal axis of the nozzle nose 50. The guide collar 47 and the nozzle nose 50 are each made from a suitable electrically non-conductive material, as a plastic material. 7

As shown in FIGS. 2 and 5, the spray nozzle of the present invention is provided with an adjustable powder spray flow control means, generally indicated by the numeral 56, and which comprises a cylindrical sleeve made from a suitable electrically nonconductive material, as a plastic material. The cylindrical sleeve 56 is provided with an internal bore 57 which extends completely therethrough and which is of a diameter sufficient to provide for a free sliding friction fit of the sleeve 56 over the outer cylindrical surface of the nozzle nose 50. The outer end of the sleeve 56 is indicated by the numeral 58 and it is disposed axially inward of the ports 55 when the inner end 59 of the sleeve 56 is seated against the flange 34 on the carrier 51. The outer cylindrical surface of the sleeve 56 is fo a size sufficient to be freely slidable within the bore 48 in the outer end of the guide collar 47 so that the collar 47 can provide longitudinal guidance to the sleeve 56 as it is moved axially within the bore 48 for powder spray pattern control purposes, as described hereinafter.

It will be seen that when the cylindrical sleeve 56 is in its retracted or inoperative position shown in FIG. 2, it does not affect the powder spray pattern, which is indicated by the broken lines emerging from the nozzle nose 50 in this figure. FIG. 3 shows the cylindrical sleeve 56 moved axially forward to a position 56a wherein it is deflecting the streams or lines of powder discharging from the nozzle nose 50 so as to deflect them into the cylindrical pattern shown in FIG. 3, and increase the range of the powder spray pattern. It will be understood, that the cylindrical sleeve 56 may be moved to any desired position relative to the nozzle nose 50 to provide a desired powder spray pattern.

It will be further understood, that the cylindrical sleeve 56 controls the powder spray pattern without the need for changing the atomizing air pressure. However, the atomizing air pressure can be changed, if desired, but the cylindrical sleeve 56 does provide powder spray pattern control under constant atomizing air pressure conditions.

In one embodiment the nozzle nose 50 was provided with 26 ports which were each of a diameter of H16 inch. The preferable range of diameters for the ports 55 is from l/32 inch diameter up to and including 4; inch diameter. The preferable range of diameters for the ports 41 is from 1/32 inch diameter up to and including l/l6 inch diameter.

The number of ports 55 employed would depend upon the size of the over-all nozzle construction and the number of pounds of powder which is desired to be deposited on workpieces within a certain period of time.

In use, an electrostatic field between the spray gun l and the object to be coated is provided in a known manner by said suitable high voltage source. The spray nozzle of the present invention is slidably mounted on the front end of the conventional spray gun shown in FIG. 1, and with the conduits l7, l8 and 19 operatively connected, as described hereinbefore. The spray pattern provided when the trigger is actuated is of the form shown by the broken lines in FIG. 2, and this spray pattern may be controlled by providing a relative movement between the sleeve 56 and the nozzle nose 50, whereby as the sleeve 56 is moved outwardly, to the position shown in FIG. 3, the conically shaped spray pattern of FIG. 2 will be restricted and controlled and changed to a cylindrical and straight line pattern.

It will be seen that when the atomizing air passes from the air chamber 23 through the ports 41, such air will be admitted to the diffusing chamber 38 after the powder has begun to expand and it performs an efficient job of breaking up the powder because of the turbulence at that point in the diffusing chamber 38.

It will also be seen that with the charging needle 42 disposed axially in the outer end of the diffusing chamber 38, an efficient ionizing charge is provided on the powder as it passes thereby. It has been found that because the entire mass of the nozzle is not acting as a charging means, the nozzle of the present invention will not hold a charge for any long interval and the charge is dissipated in a matter of a few seconds. The nozzle of the present invention may be quickly and easily disassembled for cleaning purposes in order to change powder colors. The charging needle 42 is made from a suitable conductive material, as copper and so forth.

It will be seen that the cylindrical sleeve 56 provides a powder spray pattern control means which permits the controlling of the powder spray pattern in a very precise manner. The cylindrical sleeve 56 eliminates any puffing of the powder when it exits or discharges from the nozzle nose, and is provides a continuous flow of powder which results in an improved wrap or attachment of the powder on a workpiece.

FIGS. 7, 8 and 9 illustrate a second nozzle nose embodiment generally indicated by the numeral 66 which may be employed in the spray nozzle of the present invention. The nozzle nose 66 is adapted to provide a flat or fan type spray pattern, and it includes a cylindrical body portion 67 which is provided with an axial bore 68 which is open at the rear end thereof and which extends inwardly to the inner surface 69 of the front wall 73 that forms the nose front end or tip of the nozzle nose. The inner surface 69 is substantially concave and of the same curvature as the outer convex face 70 of the nozzle nose tip with the exception of a central flat strip 69a.

The nozzle nose 66 is provided with a plurality of rows of discharge ports which are disposed in straight lines, with the middle row of said plurality of rows being on a diameter line. As shown in FIGS. 7 and 8, a certain number of ports in each of said rows of ports are disposed toward the center of the nozzle nose and are axially disposed, as indicated by the numeral 71. The ports in each row at the outer ends thereof are disposed at various outwardly diverging angles relative to the longitudinal axis of the nozzle nose, as for example, 15 as indicated by the numerals 72, 30 as indicated by the numerals 73, and 45 as indicated by the numerals 74. The ports 71 and 72 are disposed over the inner flat strip 69a.

The nozzle 66 provides a flat type or fan type spray pattern, and this pattern may be controlled in a precise manner by the cylindrical 'sleeve 65 which is slidably mounted thereover in the same manner, and which functions in the same manner, as described hereinbefore for the first nozzle nose embodiment 50 shown in FIGS. 1 through 5.

FIGS. 10 and 11 illustrate another modified embodiment of a nozzle nose employed in the present invention. The nozzle nose of FIGS. 10 and 11 is generally designated by the numeral 50b, and the parts thereof which are identical to the parts of the nozzle nose 50 of FIGS. 2 and 5 are marked with the same reference numerals followed by the small letter b." The only difference between the nozzle nose 50 and the nozzle nose 50b is that the nozzle nose 50b of FIGS. 10 and 11 is provided with a second annular row of discharge ports designated by the numeral 76 which are made in the same manner and size as the nozzle nose 50.

FIG. 12 illustrates a second embodiment of the invention in which the parts which are the same as the embodiment of FIGS. 1 through 5 have been marked with the same reference numerals followed by the small letter c. In the embodiment of FIG. 12, the atomizing air chamber 23 and the ports 41 have been deleted. The embodiment of FIG. 12 is used in small size spray guns up to about one inch carrier chamber diameter, at the large end thereof.

The powder flow air pressure in the powder supply conduit 27 in such small size guns may vary from 5 psi to 40 psi, and 'such pressures are sufficient for proper powder turbulence in the carrier chamber. The normal powder supply pressure in the conduit 27 is about l5 psi. The discharge ports 55in such small size spray guns would preferably be within the range of H32 inch diameter up to and including l/l6 inch diameter. In order to increase the powder flow for larger diameter guns, having a diameter larger than approximately 1 inch at the large end of the carrier chamber, the atomizing air chamber 23 of the first embodiment and the ports 41 would be used. Also, the discharge ports 55 for the larger guns may be increased to approximately 3/32 inch in diameter. The powder rate flow in the aforementioned small guns may vary from 15 to 16 pounds per hour, whereas the powder rate flow, for example, in a three inch outer end carrier chamber diameter spray gun may vary from 50 to 150 pounds per hour, depending upon the powder flow pressure and the atomizing air pressure employed.

The embodiment of FIG. 12 functions in the same I manner as the embodiment shown in FIGS. 1 through 5. The air pressure carrying thepowder through the conduit 27c is sufficient for providing the necessary turbulence in the carrier chamber 38c.

FIGS. 13 and I4 illustrate a modified charging needle embodiment wherein a plurality of charging needles 42d, 42d and 42d" are operatively mounted in the carrier chamber 38:]. The parts of the embodiment of FIGS. 13 and 14 which are the same as the first two embodiments of FIGS. 1 through 9 have been marked with the same reference numerals followed by the small letter d. The nozzle nose illustrated in FIGS. 13 and 14 is of the type shown in FIGS. 7, 8 and 9, but it will be understood that the nozzle nose 50 of FIGS. 1 through 5 may be used in the structure of FIGS. 13 and 14.

As shown in FIGS. 13 and 14, the charging needle 42d is axially disposed in the same manner as the needle 42 in FIGS. 2 and 5, and it is operatively connected to a conductor ring 36 in the same manner as shown in FIGS. 2 and 5. The charging needles 42d and 42d" are operatively mounted in the carrier chamber 38d in diametrically opposite positions relative to the central needle 42d. The charging needles 42d"and 42d" are operatively mounted in the carrier 31d in the same manner as the needle 42d, and they are also operatively connected to a conductor ring 36 in the same manner as the needle 42 of FIGS. 2 and 5.

The use of a plurality of charging needles, as shown in FIGS. 13 and 14, provides for lateral distribution of the charging flux along the diametrically disposed discharge ports in the nozzle nose 66d. However, the plurality of charging needles would also function in the nozzle nose 50 of FIGS. 2 and 5, or the nozzle nose 50b of FIGS. 10 and 11.

FIG. 15 is a view similar to FIG. 13, and it also illustrates the use of a plurality of charging needles which comprises the pair of charging needles 42c and 42e'. The pair of charging needles 42e and 42e' function in the same manner as described hereinbefore for the embodiment of FIGS. 13 and 14. The parts of the embodiment of FIG. 15 which are identical to the parts of the embodiments shown in FIGS. 1 through 9 have been marked with the same reference numerals followed by the smaller letter e." 7

FIG. 16 is a fragmentary, elevational section view of a modified charging needle means and nozzle nose therefor. The parts shown in FIG. 16 which are the same as the parts illustrated in FIGS. 2 and 5 have been marked with the same reference numerals followed by the small letter f. In the embodiment of FIG. 16 the charging needle 42f is extended forwardly through the conical tip 52f of the nozzle nose 50f. The nozzle tip 52f is provided with an axial passage 77 through which is extended the outer end or extension of the charging needle 42f. The outer end or extension of the needle 42f protrudes beyoi'ld the point of the tip 52f and such protruding portion of the needle extension is indicated by the numeral 78. A preferred length of the needle protruding portion 78 is from 1/32 inch to and including inch.

The extending of the charging needle through the nozzle nosereduces any arcing between the spray gun and the spray booth, or the workpiece being sprayed, to a minimum for safety purposes. The charging flux field is moved forwardly along the spray nozzle, and it has been found that any static charge on the nozzle end of the spray gun when it is shut off, is dissipated in a matter of a few seconds. The structure of FIG. 16 functions in the same manner as the'previously described embodiments, but it has been found that the structure of FIG. 16 further permits a workpiece to be efficiently sprayed with paint powder from a point further away than the prior art devices.

FIG. 17 is a fragmentary, elevational section view, similar to FIG. 16, and the parts thereof which are similar have been marked with the same reference numerals followed by the small letter g. In the embodiment of FIG. 17 a pair of laterally spaced apart charging needles 42g and 42g have been provided. The charging needles 42g and 42g are mounted in the carrier body 32g, and they are operatively connected to a conductor ring 36 in the same mariner as in the first embodiment of FIGS. 2 and 5.

The outer ends of the charging needles 42g and 423' are integrally interconnected by a transverse needle member 79 which may be made from the same material and to the same size as the needles 42g and 423'. A charging needle extension 80 is operatively mounted through an axial passage 77g in the nozzle nose tip 52 and its inner end is conductively connected to the transverse needle member 79. The outer end 81 of the needle extension 80 protrudes beyond the point of the nose tip 52. The length of the protruding needle extension end 81 would be from about l/32 inch up to and including inch. The embodiment of FIG. 17 functions in the same manner as the embodiment of FIG. 16. The needle member 79 and the extension 80 are preferably made from the same material as the needles 42g and 42g.

FIGS. 18 and 19 illustrate a slight modification of the charging needle structure of FIG. 15 in which a pair of charging needles are interconnected and provided with an extension that protrudes through the outer surface of the nozzle nose. The parts of the structure of FIGS. 18 and 19 which are the same as the structure of FIG. 15 have been marked with the same reference numerals followed by the small letter h." As shown in FIGS. 18 and 19, the charging needles 42h and 42h are interconnected at their outer ends by a transverse needle member 79h which is made from the same material and to the same size as the needles 42h and 4212'. A charging needle extension 80h extends forwardly from the interconnecting needle member 79h and through an axial passage 77!: in the nozzle nose 66h. The outer end 81h of the needle extension 80!: protrudes beyond the outer surface of the nozzle nose 66h for a suitable length of from about l/32 inch up to and including V4 inch. The embodiment of FIGS. 18 and 19 functions in the same manner as the previously described embodiments.

The term charging electrode" is used herein interchangeably with the term charging needle.

While it will be apparent that the preferred embodiments of the invention herein disclosed are well calculated to fulfill the objects above stated, it will be appreciated that the invention is susceptible to modification, variation and change.

What is claimed is:

1. In a powder spray nozzle for use with an electrostatic powder spray gun for coating objects in an electrostatic field, and wherein said gun includes an insulating barrel in which is carried a powder supply conduit connected to a pressurized source of coating powder and an electrical conductor means operatively connected to a source of electrical power, the combination comprising:

a. an electrically non-conductive nozzle body for releasable attachment to the front end of said gun barrel;

b. an electrically non-conductive carrier member operatively mounted in the front end of said nozzle body and being provided with an axially disposed powder diffusing chamber formed therein which is open at its outer end and operatively connected at its inner end to said pressurized source of coating powder;

c. an electrical charging means operatively mounted in said powder diffusing chamber and being operatively connected to said electrical conductor means for ionizing powder as it passes through said powder diffusing chamber; and,

d. an electrically non-conductive diffusing nozzle nose mounted over the outer end of said powder diffusing chamber and provided with discharge orifices for dispersing ionized powder discharged from said powder diffusing chamber into a spray pattern.

2. An electrostatic non-conductive powder spray gun nozzle as defined in claim 1, including:

a. powder spray flow control means operatively carried on said nozzle nose for relative movement thereon to control the spray pattern of the powder discharged from the nozzle nose.

3. An electrostatic powder spray gun nozzle as defined in claim 2, wherein:

a. said powder spray flow control means includes a non-conductive cylindrical sleeve adjustably mounted on said nozzle nose for movement between an inoperative position and adjusted operative positions.

4. An electrostatic powder spray gun nozzle as defined in claim 3, wherein:

a. said powder spray flow control means further includes means operatively connected to said nonconductive cylindrical sleeve for adjusting the position of said sleeve on said nozzle nose.

5. An electrostatic powder spray gun nozzle as defined in claim 1, wherein:

a. said electrical charging means comprises at least one charging electrode.

6. An electrostatic powder spray gun nozzle as defined in claim 5, wherein:

a. said charging electrode is disposed axially in said powder diffusing chamber.

7. An electrostatic powder spray gun nozzle as defined in claim 5, wherein:

a. said nozzle nose is provided with a passage therethrough for connecting the interior thereof with the atmosphere; and,

b. said charging electrode includes an extension that is disposed in said passage and protrudes beyond the outer end of said passage into the atmosphere.

8. An electrostatic powder spray gun nozzle as defined in claim 1, wherein:

a. said electrical charging means includes an extension which passes through said nozzle nose and protrudes beyond the outer surface of the nozzle nose into the atmosphere.

9. An electrostatic powder spray gun nozzle as defined in claim 8, wherein:

a. said diffusing nozzle nose includes a conically shaped outer end surface, and said discharge orifices are disposed around the inner end of said conically shaped surface and perpendicular to said conically shaped surface.

10. An electrostatic powder spray gun nozzle as defined in claim 8, wherein:

a. said diffusing nozzle nose includes a convexly shaped outer end surface, and said discharge orifices are disposed in a plurality of lines across the outer face of said convexly shaped outer end surface.

II. An electrostatic powder spray gun nozzle as defined in claim 1, wherein:

a. said electrical charging means comprises a plurality of charging electrodes.

12. An electrostatic powder spray gun nozzle as defined in claim 11, wherein:

a. said plurality of charging electrodes are longitudinally disposed in said powder diffusing chamber.

13. in a powder spray nozzle for use with an electrostatic powder spray gun for coating objects in an electrostatic field, and wherein said gun includes aninsulating barrel in which is carried a powder supply conduit connected to a pressurized source of coating powder and an electrical conductor means operatively connected to a source of electrical power, the combination comprising:

a. an electrically non-conductive nozzle body for releasable attachment to the front end of said gun barrel;

b. an electrically non-conductive carrier member operatively mounted in the front end of said nozzle body and being provided with an axially disposed powder diffusing chamber formed therein which is 13 open at its outer end and operatively connected at its inner end to said pressurized source of coating powder;

c. an electrical charging means operatively mounted in said powder diffusing chamber and being operatively connected to said electrical conductor means for ionizing powder as it passes through said powder diffusing chamber;

d. an electrically non-conductive diffusing nozzle nose mounted over the outer end of said powder diffusing chamber and provided with discharge orifices for dispersing ionized powder discharged from said powder diffusing chamber into a spray pattern;

e. said electrical charging means comprising a plurality of charging electrodes;

f. a transverse electrode member interconnecting said plurality of charging electrodes; and,

g. an electrode extension connected to said transverse electrode member and extended through said nozzle nose and beyond the outer surface of the nozzle nose into the atmosphere.

14. An electrostatic powder spray gunnozzle as defined in claim 13, wherein:

a. said diffusing nozzle includes a conically shaped outer end.

15. An electrostatic powder spray gun nozzle as defined in claim 13, wherein:

a. said diffusing nozzle nose includes a convexly shaped outer end.

16. An electrostatic powder spray gun nozzle as defined in claim 13, wherein:

a. said diffusing nozzle nose includes a conically shaped outer end surface and said discharge orifices are disposed around the inner end of said conical shape in at least one annular row, and perpendicular to said conically shaped outer end surface.

17. An electrostatic powder spray gun nozzle as defined in claim 16, wherein:

a. said discharge orifices are disposed in a plurality of annular rows.

18. An electrostatic powder spray gun nozzle as defined in claim 13, wherein: V

a. said powder diffusing chamber is conically shaped with the smaller end thereof disposed inwardly.

19. An electrostatic powder spray gun nozzle as defined in claim 18, wherein:

a. said electrical charging means includes a conductor ring carried on said carrier member and which is conductively connected to said charging means and to said electrical conductor means.

20. in a powder spray nozzle for use with an electrostatic powder spray gun for coating objects in an electrostatic field, and wherein said gun includes an insulating barrel in which is carried a powder supply conduit connected to a pressurized source, of coating powder and an electrical conductor means operatively connected to a source of electrical power, the combination comprising:

a. an electrically non-conductive nozzle body for releasable attachment to the front end of said gun barrel; 7

b. an electrically non-conductive carrier member. op-

eratively mounted in the front end of saidnozzle body and being provided with an axially disposed powder diffusing chamber formed therein which is open at its outer end and operatively connected at its inner end to said pressurized source of coating powder;

c. an electrical charging means operatively mounted in said powder diffusing chamber and being operatively connected to said electrical conductor means for ionizing powder as it passes through said powder diffusing chamber;

-d. an electrically non-conductive diffusing nozzle nose mounted over the outer end of said powder diffusing chamber and provided with discharge orifices for dispersing ionized powder discharged from said powder diffusing chamber into a spray pattern; 7

c. said powder diffusing chamber being conically shaped with the smaller end thereof disposed inwardly;

f. an atomizing air chamber formed in the front end of said nozzle body and operatively connected to a souce of pressurized atomizing air through an atomizing air conduit in said gun barrel; and,

g. said carrier member having its inner end extended into said atomizing air chamber and having a plurality of ports communicating said powder diffusing chamber with said atomizing air chamber.

21. An electrostatic powder spray gun nozzle as defined in claim 20, wherein:

a. said ports communicating said powder diffusing chamber with said atomizing air chamber are disposed forwardly from the smaller end of said conically shaped powder diffusing chamber.

22. An electrostatic powder spray gun nozzle as defined in claim 21, wherein:

a. said electrical charging means includes at least one charging electrode disposed axially in said powder diffusing chamber.

23. An electrostatic powder spray gun nozzle as defined in claim 22, including:

a. powder spray flow control means operatively carried on said nozzle nose for relative movement thereon to control the spray pattern of the powder discharged from the nozzle nose.

24. An electrostatic powder spray gun nozzle as defined in claim 23, wherein: v

a. said powder spray flow control means includes a cylindrical sleeve adjustably mounted on said nozzle nose for movement between an inoperative position and adjusted operative positions.

25.An electrostatic powder spray gun nozzle as defined in claim 13, wherein:

a. said diffusing nozzle nose includes a convexly shaped outer end surface, and said discharge orifices are disposed in a plurality of lines across the outer face of said convexly shaped outer end surface.

26. In a powder spray nozzle for use with an electrostatic powder spray gun for coating objects in an electrostatic field, and wherein said gun includes an insulatingbarrel in which is carried a powder supply conduit conected to a pressurized source of coating powder and an electrical conductor means operatively connected to a source of electrical power, the combination comprising: y

a. an electrically non-conductive nozzle body for releasable attachment to the front end of said gun barrel;

b. an electrically non-conductive carrier member opera tively mounted in the front end of said nozzle 15 16 body and being provided with an axially disposed including a flat strip which is perpendicular to the powder diffusing chamber formed therein which is longitudinal axis of the nozzle nose. open at its outer end and operatively connected at 27. An electrostatic powder spray gun nozzle as deits inner end to said pressurized source of coating fined in claim 13, including: powder; a. powder spray flow control means operatively carc. an electrical charging means operatively mounted ried on said nozzle nose for relative movement in said powder diffusing chamber and being operathereon to control the spray pattern of the powder tively connected to said electrical conductor means discharged from the nozzle nose. for ionizing powder as it passes through said pow- 28. An electrostatic powder spray gun nozzle as deder diffusing chamber; fined in claim 27, wherein:

d. an electrically non-conductive diffusing nozzle a. said powder spray flow control means includes a nose mounted over the outer end of said powder cylindrical non-conductive sleeve adjustably diffusing chamber and provided with discharge orimounted on said nozzle nose for movement befices for dispersing ionized powder discharged tween an inoperative position and adjusted operafrom said powder diffusing chamber into a spray 5 tive positions. pattern; 29. An electrostatic powder spray gun nozzle as dee. said diffusing nozzle nose including a convexly fined in claim 28, wherein:

shaped outer end surface, and said discharge oria. said powder spray flow control means further infices being disposed in a plurality of lines across the eludes means operatively connected to said cylinouter face of said convexly shaped outer end sur- 2o drical sleeve for adjusting the position of said face; and, sleeve on said nozzle nose.

f. the inner end surface of said diffusing nozzle nose 1 I JUNITED STA T E PATENT {eFFIcE E F CAT-E F CQRRECTIN 7 Patent No; '6-7;; 6 x Dated Oc vtobeyr 23 1973 y Claus Clausen and Fredefick K, Jensen It is certified that err- 0 1" afip'ears in the above-idenfifid'patent and that said Letters Patent are hereby corrected as shown below:-

Column 5;; line 44, "'abuti should be abutting Column 5, line 45, delete "abutting-'3 and-insert front -Column 6, line 50, 159" Should be" '50 Claim 2, first line, delete "nonconductive; same claim, line 3,

after "a" insert-- non-conductive I Signed and; seeied this 19th (lay of February 197A;

(SEAL) Attest:

EDWARD M.FLET01ER,JRL 1 ARSHALL DANN A gt Offi er (lomm lss lone'r of Patents FORM po'wso uo'ss) UscoMM-oc 60376-P69 U.5. GOVERNMENT PRINTING OFFICE 2 I959 35G"334 

1. In a powder spray nozzle for use with an electrostatic powder spray gun for coating objects in an electrostatic field, and wherein said gun includes an insulating barrel in which is carried a powder supply conduit connected to a pressurized source of coating powder and an electrical conductor means operatively connected to a source of electrical power, the combination comprising: a. an electrically non-conductive nozzle body for releasable attachment to the front end of said gun barrel; b. an electrically non-conductive carrier member operatively mounted in the front end of said nozzle body and being provided with an axially disposed powder diffusing chamber formed therein which is open at its outer end and operatively connected at its inner end to said pressurized source of coating powder; c. an electrical charging means operatively mounted in said powder diffusing chamber and being operatively connected to said electrical conductor means for ionizing powder as it passes through said powder diffusing chamber; and, d. an electrically non-conductive diffusing nozzle nose mounted over the outer end of said powder diffusing chamber and provided with discharge orifices for dispersing ionized powder discharged from said powder diffusing chamber into a spray pattern.
 2. An electrostatic non-conductive powder spray gun nozzle as defined in claim 1, including: a. powder spray flow control means operatively carried on said nozzle nose for relative movement thereon to control the spray pattern of the powder discharged from the nozzle nose.
 3. An electrostatic powder spray gun nozzle as defined in claim 2, wherein: a. said powder spray flow control means includes a non-conductive cylindrical sleeve adjustably mounted on said nozzle nose for movement between an inoperative position and adjusted operative positions.
 4. An electrostatic powder spray gun nozzle as defined in claim 3, wherein: a. said powder spray flow control means further includes means operatively connected to said non-conductive cylindrical sleeve for adjusting the position of said sleeve on said nozzle nose.
 5. An electrostatic powder spray gun nozzle as defined in claim 1, wherein: a. said electrical charging means comprises at least one charging electrode.
 6. An electrostatic powder spray gun nozzle as defined in Claim 5, wherein: a. said charging electrode is disposed axially in said powder diffusing chamber.
 7. An electrostatic powder spray gun nozzle as defined in claim 5, wherein: a. said nozzle nose is provided with a passage therethrough for connecting the interior thereof with the atmosphere; and, b. said charging electrode includes an extension that is disposed in said passage and protrudes beyond the outer end of said passage into the atmosphere.
 8. An electrostatic powder spray gun nozzle as defined in claim 1, wherein: a. said electrical charging means includes an extension which passes through said nozzle nose and protrudes beyond the outer surface of the nozzle nose into the atmosphere.
 9. An electrostatic powder spray gun nozzle as defined in claim 8, wherein: a. said diffusing nozzle nose includes a conically shaped outer end surface, and said discharge orifices are disposed around the inner end of said conically shaped surface and perpendicular to said conically shaped surface.
 10. An electrostatic powder spray gun nozzle as defined in claim 8, wherein: a. said diffusing nozzle nose includes a convexly shaped outer end surface, and said discharge orifices are disposed in a plurality of lines across the outer face of said convexly shaped outer end surface.
 11. An electrostatic powder spray gun nozzle as defined in claim 1, wherein: a. said electrical charging means comprises a plurality of charging electrodes.
 12. An electrostatic powder spray gun nozzle as defined in claim 11, wherein: a. said plurality of charging electrodes are longitudinally disposed in said powder diffusing chamber.
 13. In a powder spray nozzle for use with an electrostatic powder spray gun for coating objects in an electrostatic field, and wherein said gun includes an insulating barrel in which is carried a powder supply conduit connected to a pressurized source of coating powder and an electrical conductor means operatively connected to a source of electrical power, the combination comprising: a. an electrically non-conductive nozzle body for releasable attachment to the front end of said gun barrel; b. an electrically non-conductive carrier member operatively mounted in the front end of said nozzle body and being provided with an axially disposed powder diffusing chamber formed therein which is open at its outer end and operatively connected at its inner end to said pressurized source of coating powder; c. an electrical charging means operatively mounted in said powder diffusing chamber and being operatively connected to said electrical conductor means for ionizing powder as it passes through said powder diffusing chamber; d. an electrically non-conductive diffusing nozzle nose mounted over the outer end of said powder diffusing chamber and provided with discharge orifices for dispersing ionized powder discharged from said powder diffusing chamber into a spray pattern; e. said electrical charging means comprising a plurality of charging electrodes; f. a transverse electrode member interconnecting said plurality of charging electrodes; and, g. an electrode extension connected to said transverse electrode member and extended through said nozzle nose and beyond the outer surface of the nozzle nose into the atmosphere.
 14. An electrostatic powder spray gun nozzle as defined in claim 13, wherein: a. said diffusing nozzle includes a conically shaped outer end.
 15. An electrostatic powder spray gun nozzle as defined in claim 13, wherein: a. said diffusing nozzle nose includes a convexly shaped outer end.
 16. An electrostatic powder spray gun nozzle as defined in claim 13, wherein: a. said diffusing nozzle nose includes a conically shaped outer end surface and said discharge orifices are disposed around the inner end of said conical shape in at least one annular row, and perpendicular to said conically shaped outer end surface.
 17. An electrostatic powder spray gun nozzle as defined in clAim 16, wherein: a. said discharge orifices are disposed in a plurality of annular rows.
 18. An electrostatic powder spray gun nozzle as defined in claim 13, wherein: a. said powder diffusing chamber is conically shaped with the smaller end thereof disposed inwardly.
 19. An electrostatic powder spray gun nozzle as defined in claim 18, wherein: a. said electrical charging means includes a conductor ring carried on said carrier member and which is conductively connected to said charging means and to said electrical conductor means.
 20. In a powder spray nozzle for use with an electrostatic powder spray gun for coating objects in an electrostatic field, and wherein said gun includes an insulating barrel in which is carried a powder supply conduit connected to a pressurized source of coating powder and an electrical conductor means operatively connected to a source of electrical power, the combination comprising: a. an electrically non-conductive nozzle body for releasable attachment to the front end of said gun barrel; b. an electrically non-conductive carrier member operatively mounted in the front end of said nozzle body and being provided with an axially disposed powder diffusing chamber formed therein which is open at its outer end and operatively connected at its inner end to said pressurized source of coating powder; c. an electrical charging means operatively mounted in said powder diffusing chamber and being operatively connected to said electrical conductor means for ionizing powder as it passes through said powder diffusing chamber; d. an electrically non-conductive diffusing nozzle nose mounted over the outer end of said powder diffusing chamber and provided with discharge orifices for dispersing ionized powder discharged from said powder diffusing chamber into a spray pattern; e. said powder diffusing chamber being conically shaped with the smaller end thereof disposed inwardly; f. an atomizing air chamber formed in the front end of said nozzle body and operatively connected to a source of pressurized atomizing air through an atomizing air conduit in said gun barrel; and, g. said carrier member having its inner end extended into said atomizing air chamber and having a plurality of ports communicating said powder diffusing chamber with said atomizing air chamber.
 21. An electrostatic powder spray gun nozzle as defined in claim 20, wherein: a. said ports communicating said powder diffusing chamber with said atomizing air chamber are disposed forwardly from the smaller end of said conically shaped powder diffusing chamber.
 22. An electrostatic powder spray gun nozzle as defined in claim 21, wherein: a. said electrical charging means includes at least one charging electrode disposed axially in said powder diffusing chamber.
 23. An electrostatic powder spray gun nozzle as defined in claim 22, including: a. powder spray flow control means operatively carried on said nozzle nose for relative movement thereon to control the spray pattern of the powder discharged from the nozzle nose.
 24. An electrostatic powder spray gun nozzle as defined in claim 23, wherein: a. said powder spray flow control means includes a cylindrical sleeve adjustably mounted on said nozzle nose for movement between an inoperative position and adjusted operative positions.
 25. An electrostatic powder spray gun nozzle as defined in claim 13, wherein: a. said diffusing nozzle nose includes a convexly shaped outer end surface, and said discharge orifices are disposed in a plurality of lines across the outer face of said convexly shaped outer end surface.
 26. In a powder spray nozzle for use with an electrostatic powder spray gun for coating objects in an electrostatic field, and wherein said gun includes an insulating barrel in which is carried a powder supply conduit connected to a pressurized source of coating powder and an electrical conductor means operatively connected to a source of electrical power, the combination comprising: a. an electrically non-conductive nozzle body for releasable attachment to the front end of said gun barrel; b. an electrically non-conductive carrier member operatively mounted in the front end of said nozzle body and being provided with an axially disposed powder diffusing chamber formed therein which is open at its outer end and operatively connected at its inner end to said pressurized source of coating powder; c. an electrical charging means operatively mounted in said powder diffusing chamber and being operatively connected to said electrical conductor means for ionizing powder as it passes through said powder diffusing chamber; d. an electrically non-conductive diffusing nozzle nose mounted over the outer end of said powder diffusing chamber and provided with discharge orifices for dispersing ionized powder discharged from said powder diffusing chamber into a spray pattern; e. said diffusing nozzle nose including a convexly shaped outer end surface, and said discharge orifices being disposed in a plurality of lines across the outer face of said convexly shaped outer end surface; and, f. the inner end surface of said diffusing nozzle nose including a flat strip which is perpendicular to the longitudinal axis of the nozzle nose.
 27. An electrostatic powder spray gun nozzle as defined in claim 13, including: a. powder spray flow control means operatively carried on said nozzle nose for relative movement thereon to control the spray pattern of the powder discharged from the nozzle nose.
 28. An electrostatic powder spray gun nozzle as defined in claim 27, wherein: a. said powder spray flow control means includes a cylindrical non-conductive sleeve adjustably mounted on said nozzle nose for movement between an inoperative position and adjusted operative positions.
 29. An electrostatic powder spray gun nozzle as defined in claim 28, wherein: a. said powder spray flow control means further includes means operatively connected to said cylindrical sleeve for adjusting the position of said sleeve on said nozzle nose. 